1. Field
The following description relates to a method and apparatus for the varied speed reproduction of video images.
2. Description of Related Art
A technology for reproducing a video image in a three-dimensional (3D) manner has been developed.
When a person sees a screen, an image projected on the screen is formed in each eye of the person. Since human eyes are separated from each other in a horizontal direction at a predetermined distance, two-dimensional (2D) images seen by the left eye and the right eye are different from each other. A distance between two points of the images formed in the eyes is called parallax.
The human brain combines the two 2D images, that are, the left-eye image and the right-eye image, to generate a 3D image that looks realistic.
The size of a binocular disparity affects a level of a cubic effect of a subject in the 3D image which is sensed by a user.
FIGS. 1A and 1B illustrate a difference in the cubic effect between subjects having different binocular disparities sensed by a user. A cubic effect Depth sensed by a user in FIG. 1A and FIG. 1B may be expressed as Equation 1.Depth=deye2TV*dobj2obj/(dobj2obj+deye2eye)  (1)where deye2TV relates to a distance between the user and a screen of a display device, dobj2obj relates to a horizontal distance between subjects in a left-eye image and a right-eye image, and deye2eye relates to a distance between the user's left eye and right eye.
In response to sizes of the subjects being the same, as shown in FIGS. 1A and 1B, and a ratio between binocular disparities in FIGS. 1A and 1B corresponding to 1:2, a ratio between the distances dobj2obj in FIGS. 1A and 1B corresponds to 1:2.
As shown in Equation 1, the cubic effect Depth sensed by the user may be proportional to a value obtained by multiplying the distance deye2TV between a TV and the eyes by the distance dobj2obj in an X-axis direction between the subjects in the left-eye image and the right-eye image displayed on the display device, and the cubic effect Depth is inversely proportional to a value obtained by the sum of the distance deye2eye and the distance dobj2obj.
In response to the distance deye2eye between the left and right eyes and the distance deye2TV between the user and the display device being fixed, a binocular disparity of each subject determines a level of a cubic effect sensed by the user.
In response to the assumption that the distance dobj2obj in FIG. 1A being 1, the distance dobj2obj in FIG. 1B being 2, and the distance deye2eye being 1, a binocular disparity sensed by the user in FIG. 1A corresponds to 0.5*deye2TV and a binocular disparity sensed by the user in FIG. 1B corresponds to 0.67*deye2TV.
In response to the user requesting to reproduce a video image at a playback speed, frames having different depth perceptions are reproduced at playback speeds different from a normal speed. In other words, the frames have different binocular disparities. In this case, since a change in a cubic effect between the frames is higher than a change in a cubic effect in response to a video image being reproduced at a normal speed, the user may feel dizzy when focusing on the subjects.